IPv4 to IPv6 Transition

IPv6 Migration

• The IETF (Internet Engineering Task Force) created a protocol to help network administrators migrate their networks to IPv6.

IPv6 Address Format

• The preferred format for writing an IPv6 address is in hexadecimal notation, separated by colons.
• An IPv6 address has a length of 128 bits, represented as 8 groups of 4 hexadecimal digits, separated by colons.

IPv4 Address Space

• The theoretical maximum number of addresses in IPv4 is approximately 4.3 billion.

IPv6 Address Notation

• The technique used to reduce the notation of an IPv6 address by replacing a string of zeros is called zero compression.
• Zero compression can be used to remove leading zeros in each group and to replace consecutive sections of zeros with '::'.

IPv6 Address Types

• There are three types of IPv6 addresses: Unicast, Anycast, and Multicast.
• The three types of IPv6 addresses are:
  • Unicast addresses, which identify a single interface.
  • Anycast addresses, which identify multiple interfaces.
  • Multicast addresses, which identify a group of interfaces.

Unicast Addresses

• The two types of unicast addresses typically associated with an IPv6 address are Global Unicast Addresses (GUA) and Link-Local Addresses (LLA).
• Global Unicast Addresses (GUA) are globally unique and routable on the IPv6 internet.
• Link-Local Addresses (LLA) are not globally unique and are used for communication between devices on the same link.

IPv6 Unique Local Addresses

• IPv6 unique local addresses are used for local communication and are not routable on the IPv6 internet.

IPv6 Global Unicast Address (GUA)

• A GUA consists of three parts: the Global Routing Prefix, the Subnet ID, and the Interface ID.
• The Global Routing Prefix is used to create subnets.

Obtaining IPv6 Addresses

• IPv6 link-local addresses (LLA) can be obtained automatically through a router advertisement or manually through a configuration file.
• The command used to configure an IPv6 GUA on an interface in Cisco IOS is 'ipv6 address'.
• There are three methods for obtaining IPv6 addresses through ICMPv6 RA messages:
  • Stateless Address Autoconfiguration (SLAAC)
  • Dynamic Host Configuration Protocol for IPv6 (DHCPv6)
  • Manual configuration

EUI-64 Process

• The EUI-64 process is used to create the interface ID for an IPv6 address, which is 64 bits in length.
• The EUI-64 process involves inserting 'FF:FE' in the middle of a 48-bit MAC address.

Subnetting

• If the global routing prefix is a /48 and the interface ID is 64 bits, 65,536 subnets can be created.
• A 64-bit interface ID supports 18,446,744,073,709,551,616 host IPv6 addresses per subnet.
• With over 65,536 subnets to choose from, the task of the network administrator becomes more complex.

Address Conservation

• Address conservation is not a concern when using IPv6, unlike in IPv4.

Configuring IPv6

• Similar to configuring IPv4, an IPv6 subnet can be configured to be on a different subnet for each interface on a router.
• The Global Routing Prefix in an IPv6 address is used to create subnets and identify the organization's IPv6 network.